Necrotizing ulcerative gingivitis (NUG), necrotizing ulcerative periodontitis (NUP), and necrotizing stomatitis (NS), collectively termed necrotizing gingivostomatitis (NG), represent a dramatic, but rare oral infection associated with diminished systemic resistance, including HIV infection. Over a 5-year period, 68 consecutive NG patients from a population with known HIV status were evaluated and treated. Lesions were staged (modified Pindborg), and clinical findings and predictor variables were compared to 68 random control subjects without NG. Most cases (52%) were stage 1, with necrosis of the tip of the interdental papilla only; 19% were stage 2, with the entire papilla affected; 22% had necrosis of marginal (stage 3) or attached gingiva (stage 4); and 7% were more advanced, with mucosal necrosis or bone exposure. Attachment loss was a feature of stage 2 or greater NG. Beside HIV infection, significant predisposing factors included poor oral hygiene, unusual life stress, inadequate sleep, Caucasian race, age 18 to 21 years, and recent illness. Ten of 68 NG patients were HIV-positive. These patients were older than seronegative patients, less likely to be Caucasian, and maintained better oral hygiene and sleep. HIV-positive NG cases were clinically indistinguishable from HIV-negative cases in this series.